1. Field of the Invention
The present invention relates to a zoom lens, and in particular, it relates to a zoom lens in which an angle of view at a short focal length is more than 75.degree. and a zoom ratio is approximately 2.5 to 3.1.
2. Description of Related Art
There is known a zoom lens whose angle of view at a short focal length is larger than 75.degree. and whose zoom ratio is approximately 2.5 to 3. Such a zoom lens constitutes, at a short focal length, a retrofocus type in which there is a negative lens and a positive lens in this order from an object side and, at a long focal length, either a telephoto type in which there is a positive lens and a negative lens in this order from the object side or an approximate telephoto type in which there are two positive lenses having a relatively small positive refractive power on the side adjacent to an image.
However, It is practically difficult to realize a zoom lens having a large aperture and a high performance while maintaining a sufficient back focal distance.